1. Field of the Invention
The present invention relates to a structure of a multi-directional operating switch and more particularly to a structure of a multi-directional operating switch provided with plural switch contacts and a stem which can be operated in both depressing direction and tilting direction selectively.
2. Description of the Prior Art
As a conventional structure of a multi-directional operating switch there is known such a structure as shown in FIGS. 7 and 8, of which FIG. 7 is a vertical sectional view of a multi-directional operating switch and FIG. 8 is a plan view with movable contacts mounted in a housing.
In both figures, a housing 11 is formed in the shape of a bottomed box using an insulating material such as a synthetic resin, an upper side of the box being open. A central fixed contact portion 12 formed of an electrically conductive metallic material is disposed at a central of an inner bottom of the housing 11. On both opposed sides of the central fixed contact portion 12 are disposed a pair of peripheral fixed contact portions 13 also formed of an electrically conductive metallic material.
The central fixed contact portion 12 and each peripheral fixed contact portion 13 are constituted by a pair of contact pieces 12a, 12b and a pair of contact pieces 13a, 13b, respectively.
On the upper surface sides of the central fixed contact portion 12 and the peripheral fixed contact portions 13 are disposed movable contacts 14 each constituted by an electrically conductive metallic disc. The movable contacts 14 are each formed in a centrally expanded dome shape.
A stem 15 is formed of an insulating material such as a synthetic resin and is composed of a first stem 16 which constitutes a base portion and a second stem 17 which is disposed centrally of the first stem 16 so as to be movable in a depressing direction.
At both underside ends of the first stem 16 are formed a pair of depressing protuberances 16b, which are respectively in abutment against the movable contacts 14 disposed on the upper surface sides of the peripheral fixed contact portions 13. With a tilting operation of the stem 15, the corresponding movable contact 14 is depressed and the contact pieces 13a and 13b of the associated peripheral fixed contact portion 13 are rendered conductive with each other through the movable contact 14.
The second stem 17 is inserted into an insertion hole 16a formed in the first step 16 and a rod-like portion projects from the insertion hole 16a and is used an operating rod portion 17a, with a depressing protuberance 17b being formed on the side opposite to the operating rod portion 17a. The depressing protuberance 17b is in abutment against the movable contact 14 disposed on the upper surface side of the central fixed contact portion 12. When the operating rod portion 17a is depressed, the depressing protuberance 17b depresses the movable contact 14, causing the contact pieces 12a and 12b of the central fixed contact portion 12 to become conductive with each other through the movable contact 14.
A cover 18 is formed by a metallic plate, with a window hole 18a being formed therein centrally for insertion therethrough of the operating rod portion 17a of the stem 15. The cover 18 covers the upper-side opening of the housing 11 to prevent the movable contacts 14 and the stem 15 from jumping out of the housing.
In the above conventional structure of a multi-directional operating switch, however, the central fixed contact portion 12 and the peripheral fixed contact portions 13 are formed in the same plane as the inner bottom of the housing 11, and also as to the movable contacts, it is necessary for them to be disposed in the same plane as the central fixed contact portion 12 and the peripheral fixed contact portions 13 correspondingly thereto. Thus, it is necessary that the movable contacts 14 be arranged at certain intervals so as not to strike against one another. In other words, it is impossible to reduce the size of the housing 11 and hence impossible to reduce the width of the switch body.
Accordingly, it is an object of the present invention to solve the above-mentioned problems and provide a structure of a multi-directional operating switch wherein a movable contact disposed over a central fixed contact portion and movable contacts disposed over peripheral fixed contact portions can be positioned overlapping each other so that their switching operations may not interfere with one another, thus permitting the reduction in width of a switch body.
For achieving the above-mentioned object, according to a first aspect of the present invention there is provided a multi-directional operating switch comprising a housing having a bottomed receptacle portion, a central fixed contact portion disposed on an inner bottom surface of the receptacle portion, peripheral fixed contact portions disposed at peripheral positions with respect to the central fixed contact portion, a plurality of movable contacts disposed in opposition to the central fixed contact portion and the peripheral fixed contact portions, and a stem for depressing the plural movable contacts selectively to switch over the contacts from one to another, wherein the movable contacts are disposed within the receptacle portion of the housing in such a manner that in the depressing direction of the stem the movable contact disposed in opposition to the central fixed contact portion and the movable contacts disposed in opposition to the peripheral fixed contact portions are spaced a predetermined distance from each other, while in a direction perpendicular to the stem depressing direction they partially overlap each other in their external forms.
According to a second aspect of the present invention there is provided, in combination with the above first means, a multi-directional operating switch wherein the inner bottom surface of the receptacle portion of the housing comprises a first inner bottom surface for disposing the central fixed contact portion thereon and a second inner bottom surface for disposing the peripheral fixed contact portions thereon, the first and second inner bottom surfaces being different in height from each other.
According to a third aspect of the present invention there is provided, in combination with the above second means, a multi-directional operating switch wherein the first inner bottom surface is formed higher than the second inner bottom surface.
According to a fourth aspect of the present invention there is provided, in combination with the above second means, a multi-directional operating switch wherein the first inner bottom surface is formed lower than the second inner bottom surface.
Further, the stem can be operated in both depressing direction and tilting direction selectively so that when the stem is depressed, the movable contact opposed to the central fixed contact portion is depressed to turn ON the central fixed contact portion, while when the stem is tilted, the movable contact opposed to the peripheral fixed contact portion is depressed and turns ON the peripheral fixed contact portion.